scholarly journals Functional assessment of the stenotic carotid artery by CFD-based pressure gradient evaluation

2016 ◽  
Vol 311 (3) ◽  
pp. H645-H653 ◽  
Author(s):  
Xin Liu ◽  
Heye Zhang ◽  
Lijie Ren ◽  
Huahua Xiong ◽  
Zhifan Gao ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Carotid Artery ◽  
Pressure Gradient ◽  
Carotid Stenosis ◽  
Functional Assessment ◽  
Image Data ◽  
Internal Carotid Artery Stenosis ◽  
Patient Specific ◽  
Severe Stenosis ◽  
Cross Sectional

The functional assessment of a hemodynamic significant stenosis base on blood pressure variation has been applied for evaluation of the myocardial ischemic event. This functional assessment shows great potential for improving the accuracy of the classification of the severity of carotid stenosis. To explore the value of grading the stenosis using a pressure gradient (PG)—we had reconstructed patient-specific carotid geometries based on MRI images—computational fluid dynamics were performed to analyze the PG in their stenotic arteries. Doppler ultrasound image data and the corresponding MRI image data of 19 patients with carotid stenosis were collected. Based on these, 31 stenotic carotid arterial geometries were reconstructed. A combinatorial boundary condition method was implemented for steady-state computer fluid dynamics simulations. Anatomic parameters, including tortuosity (T), the angle of bifurcation, and the cross-sectional area of the remaining lumen, were collected to investigate the effect on the pressure distribution. The PG is highly correlated with the severe stenosis ( r = 0.902), whereas generally, the T and the angle of the bifurcation negatively correlate to the pressure drop of the internal carotid artery stenosis. The calculation required <10 min/case, which made it prepared for the fast diagnosis of the severe stenosis. According to the results, we had proposed a potential threshold value for distinguishing severe stenosis from mild-moderate stenosis (PG = 0.88). In conclusion, the PG could serve as the additional factor for improving the accuracy of grading the severity of the stenosis.

scholarly journals Correlation between carotid stenosis and cognitive impairment

2020 ◽  
Author(s):  
YAO HUANG ◽  
Lanying He ◽  
Feng Wang ◽  
Yuanye Ma
Keyword(s):  
Cognitive Function ◽  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Carotid Stenosis ◽  
Carotid Artery Stenosis ◽  
Internal Carotid ◽  
Internal Carotid Artery Stenosis ◽  
Artery Stenosis ◽  
Severe Stenosis ◽  
Mild Stenosis

Abstract Background Severe internal carotid artery stenosis significantly affects the cognitive function of patients, but the effect of different degree and different side of stenosis on cognitive function was still controversial.This study aims to investigate the correlation between different degrees and different sides of internal carotid artery stenosis and cognitive impairment.Methods There were 34 patients with internal carotid stenosis and 31 controls without stenosis who underwent CTA, DSA, memory scale and modified WCST. Stenosis group was divided into mild stenosis group (n=15) and moderate-severe stenosis group (n=19) according to the degree of stenosis, and was divided into left stenosis group (n=24) and right stenosis group (n=10) according to the sides. Overall vascular examination results,cognitive function scores were computed and analysised.Results Stenosis group and no-stenosis group did not differ in age,education level, BMI, hyperlipidemia, gender, hypertention, diabetes, smoking drinking and right-handedness.Stenosis group had worse memory scale and modified WCST scores for cognitive function. There were statistically significant differences in memory scale and modified WCST scores between mild stenosis group, moderate-severe stenosis group and no-stenosis group,but no differences between mild stenosis group and moderate-severe stenosis group,no differences between left stenosis group and right stenosis group.Conclusions Internal carotid artery stenosis affects the cognitive function represented by memory and executive ability significantly.

scholarly journals Hypothesis of “stroke-stop” formula: a tool for risk index determination in development of acute cerebrovascular disease in asymptomatic individuals with carotid stenosis

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Іvan Kopolovets ◽  
Peter Berek ◽  
Peter Stefanic ◽  
Dmytro Lotnyk ◽  
Rastislav Mucha ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Prospective Study ◽  
Carotid Stenosis ◽  
Carotid Artery Disease ◽  
Risk Index ◽  
Morphological Structure ◽  
Internal Carotid Artery Stenosis ◽  
Cross Sectional ◽  
Asymptomatic Individuals ◽  
Ica Stenosis

Abstract Background Extracranial carotid artery disease is considered a risk factor for developing acute cerebrovascular diseases. The paper suggests the “Stroke-Stop” formula as hypothesis for the determination of the risk of developing stroke in asymptomatic individuals with carotid stenosis. The formula is based on a mathematical calculation of the major risk factors for stroke: the degree of ICA (internal carotid artery) stenosis, the morphological structure of the atherosclerotic plaque and the level of lipoprotein-associated phospholipase A2 (Lp-PLA2) concentration. Methods The cross sectional study included 70 patients with atherosclerotic ICA stenosis. Among vascular inflammatory markers, Lp-PLA2 was determined with concentration 252.7–328.6 mg/l. The obtained results were evaluated using descriptive statistics (the frequency, percentage ratio) as well as the one-way analysis of variance (ANOVA) and chi-square test. Results The risk of stroke development is eminently increasing with the progression of ICA stenosis and elevation of Lp-PLA2 levels. In patients with echolucent plaque, the risk of stroke development was significantly higher in correlation with patients with echogenic plaque. Based on calculations using “Stroke-Stop” formula, three main groups were generated: low (< 70 points), medium (70–100 points) and high (> 100 points) risk of stroke development. Conclusions Hypothesis of “Stroke-Stop” formula is proposed for better selection of patients who should be indicated for surgical treatment and will be evaluated in prospective study. In order to verify this hypothesis, we plan to do prospective study using “Stroke-Stop” formula for ipsilateral annual stroke rate in asymptomatic individuals with carotid stenosis who receive conservative therapy.

scholarly journals Determinants of Cerebrovascular Reserve in Patients with Significant Carotid Stenosis

2020 ◽  
Author(s):  
Joseph P Archie
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Carotid Stenosis ◽  
Vascular Resistance ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Systemic Arterial Pressure ◽  
Patient Specific ◽  
Flow Reserve

AbstractIntroductionIn patients with 70% to 99% diameter carotid artery stenosis cerebral blood flow reserve may be protective of future ischemic cerebral events. Reserve cerebral blood flow is created by brain auto-regulation. Both cerebral blood flow reserve and cerebrovascular reactivity can be measured non-invasively. However, the factors and variables that determine the availability and magnitude and of reserve blood flow remain poorly understood. The availability of reserve cerebral blood flow is a predictor of stroke risk. The aim of this study is to employ a hemodynamic model to predict the variables and functional relationships that determine cerebral blood flow reserve in patients with significant carotid stenosis.MethodsA basic one-dimensional, three-unit (carotid, collateral and brain) energy conservation fluid mechanics blood flow model is employed. It has two distinct but adjacent blood flow components with normal cerebral blood flow at the interface. In the brain auto-regulated blood flow component cerebral blood flow is maintained normal by reserve flow. In the brain pressure dependent blood flow component cerebral blood flow is below normal because cerebral perfusion pressure is below the lower threshold value for auto-regulation. Patient specific values of collateral vascular resistance are determined from a model solution using clinically measured systemic and carotid arterial stump pressures. Collateral vascular resistance curves illustrate the model solutions for reserve and actual cerebral blood flow as a function of percent diameter carotid artery stenosis and mean systemic arterial pressure. The threshold cerebral perfusion pressure value for auto-regulation is assumed to be 50 mmHg. Normal auto-regulated regional cerebral blood flow is assumed to be 50 ml/min/100g. Cerebral blood flow and reserve blood flow solutions are given for systemic arterial pressures of 80, 90, 100, 110 and 120 mmHg and for three patient specific collateral vascular resistance values, Rw = 1.0 (mean patient value), Rw = 0.5 (lower 1 SD) and Rd = 3.0 (upper 1 SD).ResultsReserve cerebral blood flow is only available when a patients cerebral perfusion pressure is in the normal auto-regulatory range. Both actual and reserve cerebral blood flows are primarily from the carotid circulation when carotid stenosis is less than 60% diameter. Between 60% and 75% stenosis the remaining carotid blood flow reserve is utilized and at higher degrees of stenosis all reserve flow is from the collateral circulation. The primary independent variables that determine actual and reserve cerebral blood flow are mean systemic arterial pressure, degree of carotid stenosis and patient specific collateral vascular resistance. Approximate 16% of patients have collateral vascular resistance greater than 5.0 and are predicted to be at high risk of cerebral ischemia or infarction with progression to severe carotid stenosis or occlusion. The approximate 50% of patients with a collateral vascular resistance less than 1.0 are predicted to have adequate cerebral blood flow with progression to carotid occlusion, and most maintain some reserve. Clinically measured values of cerebral blood flow reserve or cerebrovascular reactivity are predicted to be unreliable without consideration of systemic arterial pressure and degree of carotid stenosis. Reserve cerebral blood flow values measured in patients with only moderate 60% to 70% carotid stenosis are in general too high and variable to be of clinical value, but are most reliable when measured near 80% diameter stenosis and considered as percent of the maximum reserve blood flow. Patient specific measured reserve blood flow values can be inserted into the model to calculate the collateral vascular resistance.ConclusionsPredicting cerebral blood flow reserve in patients with significant carotid stenosis is complex and multifactorial. A simple cerebrovascular model predicts that patient specific collateral vascular resistance is an excellent predictor of reserve cerebral blood flow in patients with significant carotid stenosis. Cerebral blood flow reserve measurements are of limited value without accounting for systemic pressure and actual percent carotid stenosis. Asymptomatic patients with severe carotid artery stenosis and a collateral vascular resistance greater than 1.0 are at increased risk of cerebral ischemia and may benefit from carotid endarterectomy.

WHICH MORPHOLOGIC AND HEMODYNAMIC CHARACTERISTICS PREDICT INTRACRANIAL FUSIFORM ANEURYSMS RUPTURE? A PATIENT-SPECIFIC COMPUTATIONAL FLUID DYNAMICS STUDY

2017 ◽  
Vol 17 (03) ◽  
pp. 1750070
Author(s):  
YAN CHEN ◽  
YI-BIN FANG ◽  
PENG-FEI YANG ◽  
QING-HAI HUANG ◽  
JIAN-MIN LIU
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Patient Specific ◽  
Parent Artery ◽  
Cross Sectional ◽  
3D Angiography ◽  
Cross Section Area ◽  
Increased Risk ◽  
Risk Of Rupture

To identify hemodynamic and morphological parameters leading to increased risk of intracranial fusiform aneurysms (IFA) rupture using computational fluid dynamics (CFDs). A total of 24 patient-specific fusiform aneurysms models on vertebral artery were reconstructed from 3D angiography images. 11 ruptured cases and 13 unruptured cases were included. Morphologic parameters were measured and CFD parameters were calculated using CFD simulation. The length of the aneurysm is significantly shorter in ruptured group than in unruptured group. The ratio of the width to the length of an aneurysm (WLR) and the ratio of the cross-section area to the length of an aneurysm (ALR) to the averaged cross sectional areas of the inlet and outlet of the parent artery (ALaR) were significantly higher in ruptured group compared with unruptured group. Wall shear stress (WSS) of the aneurysm was normalized to the WSS of the parent artery. Hemodynamically, only low WSS was associated with higher risk of rupture. Ruptured IFAs are shorter, have bigger WLR, ALaR, and lower WSS, compared with unruptured IFAs.

scholarly journals Time-efficient patient-specific quantification of regional carotid artery fluid dynamics and spatial correlation with plaque burden

2010 ◽  
Vol 37 (2) ◽  
pp. 784-792 ◽  
Author(s):  
John F. LaDisa ◽  
Mark Bowers ◽  
Leanne Harmann ◽  
Robert Prost ◽  
Anil Vamsi Doppalapudi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Carotid Artery ◽  
Spatial Correlation ◽  
Plaque Burden ◽  
Patient Specific

scholarly journals FEASIBILITY OF VASCULAR REMODELING PARAMETER ESTIMATION FOR ASSESSING HYPERTENSIVE PREGNANCY DISORDERS

2021 ◽  
Author(s):  
Georgios Kissas ◽  
Eileen Hwuang ◽  
Elizabeth Thompson ◽  
Nadav Schwartz ◽  
John Detre ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Ad Hoc ◽  
Disease Assessment ◽  
Patient Specific ◽  
Absolute Pressure ◽  
Cross Sectional ◽  
Arterial Network ◽  
Hypertensive Pregnancy ◽  
Value Range ◽  
Pregnancy Disorders

Hypertensive pregnancy disorders, such as preeclampsia, are leading sources of both maternal and fetal morbidity in pregnancy. Non-invasive imaging, such as ultrasound and magnetic resonance imaging (MRI), is an important tool in predicting and monitoring these high risk pregnancies. While imaging can measure hemodynamic parameters, such as uterine artery pulsatility and resistivity indices, the interpretation of such metrics for disease assessment rely on ad-hoc standards, which provide limited insight to the physical mechanisms underlying the emergence of hypertensive pregnancy disorders. To provide meaningful interpretation of measured hemodynamic data in patients, advances in computational fluid dynamics can be brought to bear. In this work, we develop a patient-specific computational framework that combines Bayesian inference with a reduced-order fluid dynamics model to infer remodeling parameters, such as vascular resistance, compliance and vessel cross-sectional area, known to be related to the development of hypertension. The proposed framework enables the prediction of hemodynamic quantities of interest, such as pressure and velocity, directly from sparse and noisy MRI measurements. We illustrate the effectiveness of this approach in two systemic arterial network geometries: an aorta with carotid and a maternal pelvic arterial network. For both cases, the model can reconstruct the provided measurements and infer parameters of interest. In the case of the maternal pelvic arteries, the model can make a distinction between the pregnancies destined to develop hypertension and those that remain normotensive, expressed through the value range of the predicted absolute pressure.

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